With the advance of the liquid crystal display techniques, portable liquid crystal television receivers having screen sizes of 2 to 4 inches are commercialized, and the number of viewers who receive ordinary television broadcasting by using such small-screen liquid crystal television receivers is increasing. Also, ground-wave digital broadcasting is scheduled to be started in the near future, so portable apparatuses (e.g., Japanese Patent Application Laid-Open No. 2003-101898) capable of displaying broadcast digital images or digital images from the Internet are being developed.
On the other hand, various programs of ordinary television broadcasting are presumably produced by assuming receivers having screen sizes of about 14 to 30 inches.
Recently, HDTV (High Definition Television: high-quality television or high-resolution television) broadcasting is also started in addition to the ordinary broadcasting described above, in accordance with the introduction of the digital broadcasting techniques. With the start of the ground-wave digital broadcasting, the number of these HDTV programs will probably increase.
Programs of this HDTV are presumably produced by assuming screen sizes of about 30 to 50 inches or more as display conditions.
Additionally, the ability to display motion images of mobile apparatuses such as a cell phone, digital camera, camcorder, car navigation system, and notebook personal computer (PC) is rapidly advancing. Therefore, it is expected that motion images are generally played back on small screens of about 1.5 to 5 inches in the near future.
If, however, programs of the ordinary television broadcasting described above are viewed on portable liquid crystal television receivers of about 2 to 3 inches, the faces and expressions of cast are difficult to discriminate, and characters (e.g., signs in landscapes and headlines in papers) taken by cameras are difficult to read.
In particular, viewers will probably view programs of television broadcasting on cell phones and play back programs by using the DVD playback function of car navigation systems more often. Since the dependence on information acquisition from mobile apparatuses is thus increasing, it is necessary to alleviate the difficulties of viewing as described above.
Furthermore, with the progress of digital information, the resolution of motion images of, e.g., HDTV is more and more increasing as described above. This increases the difference between the expected display size when a program is produced and a small screen (as a part of diversification) which is the actual display size.
As a method of eliminating these inconveniences, an apparatus having a function of displaying an image by enlarging a part of the image during viewing is commercialized. However, a user must manually set the magnification and the (central) position of enlargement for each image. This can be done for still images by taking a certain time. For motion images, however, manually changing these two factors moment by moment is presumably a difficult operation which practically no general user is able to perform.